Abstract: Objectives: This study has been done to investigate the effects of foliar spraying of potassium nitrate at different concentrations and times for increasing the fruit and oil productivity and quality of Jatropha curcas trees. Methodology: Jatropha curcas trees treated with three concentrations (0.5, 1.0 and 1.5%) of KNO3 either pre and/or post bloom. Changes in leaf mineral content, flowering, fruit yield and seed oil content and their chemical characteristics were determined. Several oil properties as well as oil content, acid, peroxide and iodine values were measured too. Results: The results showed that all foliar spraying with different potassium nitrate (KNO3) concentrations and times revealed a pronounced increase in leaf mineral contents. Also, KNO3 spraying enhanced fruit yield and seed physical and chemical characteristics compared with control trees. The best results, with regards to leave mineral N, P and K were found due to foliar application with 1.5% twice and 1% once. In addition spraying potassium nitrate at 1% once which superior to increase the number of flowers, fruits per inflorescences, seed weight and oil content. Total seed weight and volume were obtained under spraying potassium nitrate at 1.5% twice. Foliar spraying of potassium nitrate 1% had the highest content of seed oil and its iodine value. Meanwhile, a good oil quality that had lowest oil acidity and peroxide value was observed with potassium nitrate concentration at 1.5% compared to untreated trees (control). Conclusion: The potassium nitrate had a positive effect of leaf mineral content with improving fruit yield, seed physical and chemical properties with greatest results at 1% potassium nitrate sprayed once as compared with control.